Field
The invention is in the field of Stay-In-Place decking forms for constructing concrete decking.
State of the Art
It is currently common practice in the construction of bridges, such as highway bridges, to erect a series of parallel bridge support girders in the form of I beams. Deck pans, such as corrugated metal pans, are installed between the parallel girders to close the space between the girders and provide a receiving form for concrete poured across the pans and girders to form a concrete bridge deck. The deck pans are supported between the girders by the horizontally extending surfaces of angle irons which extend along the longitudinal sides of the girders. The angle irons are attached by welding to the ends of straight flat straps which extend over the top surface of the girders. It is important to mount the deck pans at a desired height with respect to the upper surfaces of the girders so as to provide support for a desired thickness of the concrete deck and surface contour when concrete is poured into the pans and across the tops of the girders and smoothed to provide a smooth top concrete surface for the bridge. Since the deck pans are supported by the angle irons, it is important that the angle irons which support the deck pans at the desired height along the sides of the girders be properly secured by the straps at the desired height. Therefore, the vertical positioning of the angle irons along the sides of the girders is important. Once the girders are erected, the top surface of the girders are surveyed to determine the distance down from or up from the top of the girders to mount the angle irons. As the girders are surveyed, it is determined where the angle irons should be positioned with respect to the top surface of the girder to provide the desired top surface contour of the concrete deck. The determined position of the angle iron at a particular survey location along the length of the support girder is marked on the top surface of the support girder usually as either a “−” meaning “cut” or “+” meaning “fill” along with a measurement such as ½, meaning ½ inch, 1 meaning 1 inch, 2½ meaning 2½ inches, etc. with the “−” meaning to place the horizontal flange of the angle iron the indicated distance below the top of the top flange of the support girder, or the “+” meaning to place the horizontal flange of the angle iron the indicated amount above the top of the top flange of the support girder. The angle irons are then held in proper position by workers on the erected girders and are welded to the ends of the straps placed on the top of the top flange of the girders, again, by workers on the girders, while being held in place. This is a difficult and time consuming job. Further, it is important that when welding the angle irons to the straps on the girders, particularly with steel girders, that no welding arc between the angle irons or straps and the girder occur. In addition, it is important that no arcing occur between the welding equipment or wires to the welding equipment and the girders. Any arcing to a steel girder can damage the girder requiring expensive examination and repair of the girder. A further concern is that the welding produces toxic fumes. With workers holding the angle irons in proper position against the straps and other workers welding the ends of the straps to the angle irons, all in cramped conditions on top of the girder which is generally a significant height above the ground, it is difficult to keep workers from inhaling the toxic fumes.
It has been recognized that it would be advantageous to be able to more easily position and adjust the position of the deck pans when installing the deck pans between the bridge girders.